ul,li{
    list-style-type: none;
    margin: 0px;
    padding: 0px;
}
ul{
    overflow: hidden;
    margin: 20px auto; 
    border:1px red solid;
    width: 720px;
}
ul li{
    float: left;
}
ul li img{
    width: 240px;
    height: 135px;
    display: block;
}
#zhezhao{
    height: 270px;
    width: 720px;
    margin: 0px auto;
    background-color: black;
    opacity: 0.5;
    margin-top: -290px;
    display: none;
}
#bigpic{
    width:360px;
    height:205px;
    position:absolute;
    left:50%;
    top:60px;
    transform: translateX(-50%);
}
#closeFlag{
    border: 1px red solid;
    background-color: red;
    height: 16px;
    width: 16px;
    text-align: center;
    line-height: 16px;
    position: absolute;
    left: 820px;
    top: 60px;
    display: none;
}
